Polyvinyl acetal resin sheet containing ethoxyethyl maleate



Patented Nov. 12, 1940 PATENT OFFICE POLYVINYL ACETAL RESIN SHEET CON-TAININ G ETHOXYETHYL MALEATE Donald R. Swan, Rochester, N. Y., assignorto Eastman Kodak Company, Rochester, N. Y., a corporation of New JerseyNo Drawing.

Application December 14, 1939,

Serial No. 309,237 1 Claim. (01. zoo-sci This invention relates topolyvinyl acetal resin sheets, and more particularly to sheets suitablefor the manufacture ofsafety glass.

One object of my invention is to produce compositions of matter whichcan be made into transparent sheets suitable for use in laminated,shatter-proof glass. Another object is toproduce compositions which canbe rolled, extruded, molded, or otherwise worked into relatively thicksheets and massive plastics. Other objects will hereinafter appear.

I have discovered that ethoxyethyl maleate is a useful plastlcizer forcertain polyvinyl acetal resins, namely, the polyvinyl butyraldehydeacetal resins. Moreover, I have discovered that when 40 or more parts ofethoxyethyl maleate is used with 100 parts of polyvinyl-butyraldehydeacetal resin, an unusual and remarkable eflfect is ob-,

tained which I may call elasticizing." That is to say, a sheet ofpolyvinyl butyraldehyde acetal -resin containing about 40 or more partsor ethoxyethyl maleate per 100 parts of resin possesses the propertywhich, in the rubber industry, is known as nerve": namely, the propertyof stretching to a considerable extent when tension is exerted upon it,and returning to its original dimensions when the tension is released.This property renders such sheets, which I shall call rubbery sheets,particularly useful in the manufacture of shatter-proof glass.

Sheets for use in laminated glass may be made by dissolving thepolyvinyl butyraldehyde acetal resin and the ethoxyethyl maleate in asuitable volatile solvent or solvent mixture, such, for in- 35 stance,as acetone, methanol, acetone-methanol mixtures, ethylenechloride-methanol mixtures, etc., about 300 to 500 or more parts of thesolvent or solvent mixture being used per 100 parts of the resin. Thesolution is then cast as a sheet, the volatile solvent evaporated, andthe sheet stripped from the casting surface.

Sheets for use in laminated glass may also be made without the use ofvolatile solvent by extrusion, for example, in the manner set forth inapplication Serial No. 147,934 of John S. Kimble and Ernest C. Blackard,filed June 12, 1937. For example, 40 or more parts of ethoxyethylmaleate and 100 parts of a polyvinyl butyraldehyde acetal resin may bemixed in a suitable, jacketed mixer at a low temperature, for exampleC., and the mixture may then be worked on hot rolls, in m the mannerdescribed in U. S. Patent 2,048,686 of i F. R. Conklin, until completehomogenization has taken place. The mass thus produced may then beextruded through an annular die, and the tube so formed slit to form asheet. The polyvinyl 'acetal resins can be prepared by reactingpolyvinyl alcohol with an aldehyde in the presence of an acetalcondensation catalyst,

e. g. a mineral acid. These resins can also be prepared bysimultaneously de-esterifying a polyvinyl aliphatic ester and reactingthe de-esterification product with an aldehyde in the presence of ade-esterifying catalyst and acetal condensation catalyst. Mineral acids.are catalysts for both de-esterification and acetal formation.

Examples of the preparation of polyvinyl butyraldehyde acetal resins maybe found in U. S. Patent 2,044,730, Examples 2, 5 and 6; British Patent466,598, Example 5; French Patent 813,303, Example 1; French Patent813,514,.Examples 1, 2, o 3 and 4; and British Patent 459,878, Examples1, 2, 5, 6, 7, 8, 9 and 10.

What I claim as my invention and desire to be secured by Letters Patentof the United States A transparent, rubbery sheet comprising 100 partsof a polyvinyl butyraldehyde acetal resin .and at least 40 parts,approximately, of ethoxyethyl maleate.

, DONALD R. SWAN. o

